Digital audio system

ABSTRACT

A method and system for limiting transmission to a single operator is provided. The system and method determines if another user in the audio system is currently transmitting before allowing a new transmission from another user to proceed. This assures that the only one member of the vehicle crew can transmit at a time, limiting the opportunity for outputs from multiple users to garble the transmission. In another embodiment of the present invention, a system and method are provided that allows for the transmission of aural warning on a digital bus. The system and method allows different types of warnings to be delivered to vehicle crew members throughout the vehicle. This facilitates efficient and reliable distribution of warnings to remote crew members. In another embodiment of the present invention, a system and method are provided that notifies the user of an audio system when all outputs of the audio system have been disabled. This provides warnings to those users who may otherwise be unaware that the system outputs have been disabled.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional PatentApplication No. 60/324,035, filed Sep. 20, 2001.

BACKGROUND OF THE INVENTION

[0002] 1. Technical Field

[0003] This invention generally relates to electronic systems, and morespecifically relates to distributed audio systems.

[0004] 2. Background Art

[0005] Modern life is becoming more dependent upon electronic systems.Electronics devices have evolved into extremely sophisticated devices,and may be found in many different applications. As electronics becomemore integrated into daily life, their ability to communicate and worktogether becomes a greater and greater necessity.

[0006] The ability for electronic devices to work together isparticularly problematic where the multiple remote devices are linkedtogether. In many applications, remote devices must share limitedresources to function properly. For example, in some distributed audiosystems, remote audio devices must share transmission paths. Wheremultiple remote audio devices share transmission paths simultaneous useof the transmission path can result in garbled and incoherent audio.This can be problematic in some situations and dangerous in others.

[0007] For example, in aircraft communication systems multiple crewmembers may all be linked to one transmission system. When multiple crewmembers attempt to use the transmission system at the same time, theresulting transmission can be garbled and incoherent. This is especiallyproblematic in aircraft communication systems because incoherenttransmissions may be misinterpreted as indicative of a security problemon the aircraft

[0008] Unfortunately, in the past it has been difficult to provide theneeded sharing of distributed audio systems without introducing thepossibility of incoherent transmissions that result from multipletransmission sources all transmitting at once. Thus, what is needed isan improved system and method for selectively controlling transmissionin shared distributed audio systems.

BRIEF SUMMARY OF THE INVENTION

[0009] The present invention provides a method and system for limitingtransmission to a single operator. The system and method determines ifanother user in the audio system is currently transmitting beforeallowing a new transmission from another user to proceed. This assuresthat only one member of the vehicle crew can transmit at a time,limiting the opportunity for outputs from multiple users to garble thetransmission.

[0010] In another embodiment of the present invention, a system andmethod are provided that allows for the transmission of aural warningson a digital bus. The system and method allow different types ofwarnings to be delivered to vehicle crew members throughout the vehicle.This facilitates efficient and reliable distribution of warnings toremote crew members.

[0011] In another embodiment of the present invention, a system andmethod are provided that notify the user of an audio system when outputsof the audio system have been disabled. This provides warnings to thoseusers who may otherwise be unaware that the system outputs have beendisabled.

[0012] The foregoing and other objects, features and advantages of theinvention will be apparent from the following more particulardescription of a preferred embodiment of the invention, as illustratedin the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

[0013] The preferred exemplary embodiment of the present invention willhereinafter be described in conjunction with the appended drawings,where like designations denote like elements, and:

[0014]FIG. 1 is a schematic view of a distributed audio system;

[0015]FIG. 2 is a schematic view of audio device;

[0016]FIG. 3 is a flow diagram of a method for granting access to atransmitter;

[0017]FIG. 4 is a schematic view of an apparatus for granting access toa transmitter;

[0018]FIG. 5 is a schematic view of an apparatus for presenting auralwarnings;

[0019]FIG. 6 is a schematic view of an apparatus for visual notificationof disabled audio.

DETAILED DESCRIPTION OF THE DRAWINGS

[0020] The present invention provides a method and system for limitingtransmission to a single operator. The system and method determine ifanother user in the audio system is currently transmitting beforeallowing a new transmission from another user to proceed. This assuresthat only one member of the vehicle crew can transmit at a time,limiting the opportunity for outputs from multiple users to garble thetransmission.

[0021] In another embodiment of the present invention, a system andmethod are provided that allow for the transmission of aural warning ona digital bus. The system and method allow different types of warningsto be delivered to vehicle crew members throughout the vehicle. Thisfacilitates efficient and reliable distribution of warnings to remotecrew members.

[0022] In another embodiment of the present invention, a system andmethod are provided that notify the user of an audio system when outputsof the audio system have been disabled. This provides warnings to thoseusers who may otherwise be unaware that the system outputs have beendisabled.

[0023] The systems and method are particularly applicable to aircraftaudio systems. In aircraft audio systems, several audio panels arelocated throughout the aircraft to facilitate communication between crewmembers and/or ground stations. In these applications, each audio paneltypically includes a microphone input and a speaker output. Each audiopanel is connected to a bus. Thus, audio information can be received ateach microphone unit and put on the bus for distribution to other audiopanels, where it is outputted by the speakers on the audio panels. Thisdistributed audio system thus allows crew members at different locationsthroughout the plane to effectively communicate to each other.

[0024] In aircraft, the audio quality provided by the distributed audiosystem is of paramount importance. Turning now to FIG. 1, an exemplarydistributed audio system 100 is illustrated schematically. Thedistributed audio system 100 includes audio devices 1-5 and audioprocessor 6, coupled together with bus 104. The distributed audio system100 facilitates communication between people at remote locations, suchas between different crew members of an aircraft. Audio communication isreceived at each audio device, and is transmitted across the bus 104 tothe other audio devices where it is outputted by speakers on thosedevices. The bus 104 is preferably a digital bus that uses multiplexingto allow communication from each audio device to every other audiodevice in the system 100 on a single bus.

[0025] As will be explained in greater detail below, the audio processor6 also receives bus transmissions from the audio devices 1-5. The audioprocessor 6 demultiplexes bus transmissions to generaterequest-to-transmit signals and audio signals from any of the audiodevices 1-5 that are transmitting. The demultiplexed bus transmissionscan then be passed to a transmitting device to send the communicationoff the vehicle. The audio processor 6 also allows aural warnings fromvarious warning systems to be placed on the bus 104 and delivered tocrew members through audio devices 1-5.

[0026] Turning now to FIG. 2, a more detailed schematic view of anexemplary audio device 200 is illustrated. The audio device 200 includesa bus I/O, a microphone input, a speaker output, an analog-to-digitalconverter (ADC) and a digital-to-analog converter (DAC). The microphoneinput receives audio communication from a user and sends it to the ADC,where it is converted to digital and put on the bus I/O. The DACreceives audio signals from the bus I/O and passes the converted signalsto the speaker where they are outputted back the user. The microphoneinput can be any suitable type of audio input that converts sound wavesinto a suitable electrical signals, including headset microphonescommonly used in aircraft, telephonic devices, and other input devices.The speaker output can be any suitable audio output that convertselectrical signals to audible sound, including loudspeakers, headphones,intercom systems, telephonic devices and other such devices.

[0027] The ADC and DAC can be any suitable type of converter. Forexample, they can comprise linear converters that convert 16 bit audioto a 16 bits per sample signal. These samples can then be converted to 8bits per sample so two samples can be transmitted at a time at theslower rate.

[0028] Likewise, the bus I/O can be any suitable type of bus interface.In one example, the bus is a digital time multiplexed bus. In this typeof bus, each audio device transmits in its own specified time slot. Insuch the bus I/O could comprise a CODEC that encodes data to be put onthe bus and decodes data from the bus, using any suitable encodingscheme. The bus I/O thus receives audio samples taken by the microphoneinput and converted by the ADC and encodes those samples into a formatsuitable for digital bus transmission. The bus I/O then puts thosesamples on the bus at a time slot specified for the audio device.Likewise, the bus I/O receives signals from the time slots associatedwith other audio devices and the audio processor. These signals can bedecoded, filtered and summed, and the resulting output passed to theDAC. The DAC converts the resulting output and sends it to the speakerfor outputting to the user.

[0029] The distributed audio system and audio devices illustrated inFIGS. 1 and 2 thus facilitates communication between people at remotelocations, such as between different crew members of an aircraft. Audiocommunication can be generated at any audio device, placed on the bus,and delivered to the other audio devices where it is outputted byspeakers on those devices. The system also allows for crew members atdifferent audio devices to transmit off the vehicle through the audioprocessor 6. Specifically, the audio processor 6 also receives bustransmissions from the audio devices 1-5. The audio processor 6demultiplexes bus transmissions, which can then be passed to atransmitting device to send the messages off the vehicle.

[0030] Turning now to FIG. 3, a method 194 is illustrated for limitingtransmission capability to a single operator of a vehicle (not shown)according to a preferred exemplary embodiment of the present invention.The method 194 begins with a determination as to whether a first userhas requested a transmission capability 196. If the first user hasrequested a transmission capability, the method continues with anevaluation of whether the second user is currently transmitting 198. Ifthe second user is currently transmitting, the first user is deniedaccess to the transmitter 200. Otherwise, if the second user is notcurrently transmitting, the first user is provided access to thetransmitter 202. Similarly, the method 194 is executed for the seconduser, and the second user is denied access if requesting a transmissioncapability while the first user is currently transmitting and providedaccess if the first user is not currently transmitting. It should beunderstood that while the method 194 is described with reference to onlytwo exemplary users, it is applicable to audio systems that include morethan two users. In those cases, the additional users will take on therole of the first user or the second user described above.

[0031] Turning now to FIG. 4, an apparatus 400 presented as a functionallogic diagram illustrating how the above-described method might beimplemented in accordance with the present invention. It should also beunderstood however, that the function can also be implemented in wholeor in part using different circuit systems as well as known softwaretechniques.

[0032] In FIG. 4, the apparatus 400 receives four signals, ON1, ON2,AUD1 and AUD2. ON1 and ON2 comprise request-to-transmit signals that aresent to identify that a user has requested transmission. AUD1 and AUD2comprise the audio signals received from the audio device. As discussedabove, each audio device on the distributed audio system preferablycommunicates to other audio devices and to the audio processor using amultiplexed bus. Transmissions on the bus preferably include encodedrequest-to-transmit signals and audio signals from any transmittingaudio devices. An audio processor receives the bus transmission anddemultiplexes the bus transmissions to generate the separaterequest-to-transmit signals (e.g., ON1 and ON2) and the audio signals(e.g., AUD1 and AUD2).

[0033] These request-to-transmit signals (ON1 and ON2) and audio signals(AUD1 and AUD2) are delivered to apparatus 400. The apparatus 400selectively delivers the AUD1 and AUD2 signals to the transmitter fortransmission off the vehicle. Specifically, apparatus 400 prevents morethan one of the audio signals AUD1 and AUD2 from being transmitted atthe same time.

[0034] In apparatus 400, AND function 402 has a first input configuredto receive the first request-to-transmit signal (ON1), which is logical“1” when a first user requests transmission access to a transmitter 420.This corresponds, for example, to a first user depressing thepush-to-talk switch on a first microphone. The output of the first ANDfunction 402 is applied to a clocked logic gate 410. The clocked logicgate 410 also receives a clock signal input. The clocked logic gate 410passes the output of the first AND function 402 when it receives clocksignal inputs. This helps prevent the formation of indeterminate statesthat could otherwise arise in the feedback loops. The output of theclocked logic gate 410 is applied to the input of an inverter 408 and anaudio transmission gate 416. A second input to audio transmission gate416 is coupled to receive an audio signal (AUD1) which corresponds tothe actual audio signals generated by the first user, as for example, bymaking an announcement over a passenger address system or other forms ofinternal or external transmission. AND function 404 has a first inputcoupled to the output of inverter 408 and a second input coupled to asecond request-to-transmit signal (ON2), which indicates that a seconduser is attempting to transmit. That is, ON2 becomes a logical “1” whenthe second user depresses a switch on a microphone. The output of ANDfunction 404 is applied to a second clocked logic gate 412. The clockedlogic gate 412 also receives the clock signal input, and passes theoutput of AND function 404 when it receives clock signal inputs. Thisagain helps prevent the formation of indeterminate states in thefeedback loops. The output of the clocked logic gate 412 is applied tothe input of an inverter 406 and an audio transmission gate 418. Asecond input of the audio transmission gate 418 is coupled to receiveAUD2, which corresponds to the audio being generated by the second user.Finally, the outputs of the first audio transmission gate 416 and thesecond audio transmission gate 418 are applied to the first and secondinputs of an audio summing device 414. The audio summing device 414 sumsthe outputs of first audio transmission gate 416 and the second audiotransmission gate 418 and passes the summed output to the transmitdevice 420.

[0035] The apparatus 400 operates as follows. Assume that ON1 is alogical “1” indicating that a first user has requested access totransmit device 420, and further assume that the second input of ANDfunction 402 is a logical “1”. The output of AND function 402 istherefore a logical “1” allowing the first operators audio (AUD1) topass through audio transmission gate 416 and thus be applied to theaudio summing device 414 and outputted on transmit device 420.

[0036] The output of AND function 402 is clocked and inverted byinverter 408, and then also applied to the first input of AND function404. Thus, the output of inverter 408 is a logical “0”, disabling ANDfunction 404 and transmission gate 418 thus preventing any audiogenerated by a second user from reaching audio summing device 414. Theoutput of AND function 404 (logical “0”) is clocked and inverted byinverter 406 producing a logical “1” at the second input of AND function402. Thus, it can be seen that if the first operator has access to thetransmission device 420, the apparatus will deny any request for accessby a second operator. In a similar fashion, if the second operator hasaccess to the transmission device 420 (i.e., a logical “1” at the outputof AND function 404) a logical “0” will appear at the output of inverter406, thus disabling AND function 402 and preventing transmission throughaudio transmission gate 416.

[0037] The embodiments of the present invention thus provide a methodand system for limiting transmission to a single operator. It should beunderstood that the method and apparatus described with reference toFIGS. 3 and 4 are applicable to audio systems that include a largenumber of users. For example, the system and method can be applied tothe distributed audio system 100 of FIG. 1, where five audio devicesallow communication between five crew members on a vehicle. There thesystem and method can be used to limit transmission to one communicationfrom one of the five audio devices. Those skilled in the art will alsorecognize that the logic levels described here are merely exemplary, andthat apparatus 400 could instead by implemented using different logiclevels and/or different logic structures.

[0038] In another embodiment of the present invention, a system andmethod are provided that allow for the transmission of aural warning ona digital bus. The system and method allows different types of warningsto be delivered to vehicle crew members throughout the vehicle. Thisfacilitates efficient and reliable distribution of warnings to remotecrew members. Additionally, because the system and method transmits theaural warnings on a digital bus, the need for running dedicated audiolines for each of these warning signals is eliminated. In a largevehicle with multiple crew members, this can greatly reduce the amountof wiring needed in the vehicle.

[0039] Returning briefly to FIG. 1, the audio system 100 again includesfive audio devices 1-5 connected to each other with audio bus 104. Eachof the five audio devices 1-5 includes a speaker output for deliveringaudio to a crew member. Also included in audio system 100 is the audioprocessor 6. The audio processor 6 is configured to receive systemwarnings and pass aural warnings to the crew members at each of theaudio devices 1-5. The audio processor 6 thus allows warning signals tobe delivered to crew members using the same bus system that is used forcommunication between crew members.

[0040] Turning now to FIG. 5, an exemplary audio processor 502 isillustrated as part of a communication system 500 for presenting auralwarnings. The audio processor 502 is configured to receive warningsignals and pass an aural warning to the bus. For example, the audioprocessor 502 is configured to receive a ground proximity warningsignal, a collision and avoidance warning signal, and a fire warningsignal. The received warning signals are processed by the audioprocessor 502. This can include conversion of any analog warning signalsto digital warning signals. The digital warning signals are provided tothe digital bus 104 (FIG. 1) which distributes the digital warning toall of the audio devices 1-5. Each audio device 1-5 receives the digitalwarning signal and converts it using its DAC, and outputs it to the userusing its speaker output (FIG. 2). Those skilled in the art will thusappreciate that the system provides an efficient and effective digitaldistribution of warning signals to crew members at remote locationsthroughout the vehicle. Specifically, the system reduces wiringrequirements by sending aural warnings across the same digital bus usedfor crew communications. This reduces wiring needs and can improve theefficiency of the system.

[0041] In another embodiment of the present invention, a system andmethod are provided that notifies the user of an audio system when alloutputs of the audio system and have been disabled. This provideswarnings to those users who may otherwise be unaware that the systemoutputs, have been disabled. In modern audio systems, traditional volumeknobs have been replaced with electronic volume control systems. Whileoffering many advantages over traditional volume knobs, the electronicvolume control systems have some significant disadvantages. One of theseis that the state of the audio system cannot be readily ascertained byvisual examination of the volume knob. This means that a user of anaudio system may inadvertently turn the volume down below audible levelsand have no easy way to ascertain that the volume has been turned down.Such a user may miss critical information, such as air traffic controlcommands transmitted through the system.

[0042] Additionally, in systems that provide multiple selective outputs,a user may turn off the volume for the external speaker, intending torely instead on a headphone output. Such a user may not immediatelyrealize that that volume on the headphone output has been previouslyreduced below audible levels.

[0043] The embodiments of the present invention provide visualnotification to a user when the output volume of a system has beenturned below a specified level. This alerts the user that the volume hasbeen reduced, warning the user that they may not hear communication orwarnings on the system.

[0044] Turning now to FIG. 6, an apparatus 600 is illustrated forvisually notifying a vehicle operator that all audio has been disabled(i.e., turned off) in accordance with a preferred exemplary embodimentof the present invention. The apparatus 600 receives a plurality ofdisable signals (608, 610, 612) from a plurality of activation devices(614, 616, 618) respectively, generated by a plurality of audio sources(620, 622, 624), respectively. The disable signals (608, 610, 612) fromthe plurality of activation devices (614, 616, 618) can be logical “1”if an audio source is deactivated (i.e., “off”) and a logical “0” if theaudio source is activated (i.e., “on”) and /or can be logical “1” if themagnitude of the volume of an audio source is less than a predeterminedvolume level and a logical “0” if the magnitude of the volume of theaudio source is greater than or equal to the predetermined level.

[0045] The apparatus 600 also comprises coincidence function 626 (e.g.,an AND operator) that evaluates each of the disable signals (608, 610,612) and generates an output signal 228 if all the disable signalsindicate that each of the plurality of audio sources (620, 622, 624) aredisabled. The output signal is provided to a display 630 that generatesa visual indication if all the audio sources are disabled, such as“AUDIO OFF”. The display 630 can be further configured to generatevisual effects that are designed to attract the attention of a vehicleoperator, such as blinking text or symbol on the display 630.

[0046] The present invention thus provides a method and system forlimiting transmission to a single operator. The system and methoddetermines if another user in the audio system is currently transmittingbefore allowing a new transmission from another user to proceed. Thisassures that the only one member of the vehicle crew can transmit at atime, limiting the opportunity for outputs from multiple users to garblethe transmission. In another embodiment of the present invention, asystem and method are thus provided that allows for the transmission ofaural warning on a digital bus. The system and method allows differenttypes of warnings to be delivered to vehicle crew members throughout thevehicle. This facilitates efficient and reliable distribution ofwarnings to remote crew members. Finally, in a third embodiment of thepresent invention, a system and method are thus provided that notifiesthe user of an audio system when all outputs of the audio system havebeen disabled. This provides warnings to those users who may otherwisebe unaware that the system outputs have been disabled.

[0047] The embodiments and examples set forth herein were presented inorder to best explain the present invention and its particularapplication and to thereby enable those skilled in the art to make anduse the invention. However, those skilled in the art will recognize thatthe foregoing description and examples have been presented for thepurposes of illustration and example only. The description as set forthis not intended to be exhaustive or to limit the invention to theprecise form disclosed. Many modifications and variations are possiblein light of the above teaching without departing from the spirit of theforthcoming claims.

1. An apparatus comprising: a) a bus, the bus transmitting a bus signal,the bus signal comprising a plurality of audio signals from a pluralityof audio devices; b) an audio processor, the audio processor coupled tothe bus and receiving the bus signal, the audio processor determining ifone of the plurality of audio signals is being transmitted on atransmitter, the audio processor preventing other of the plurality ofaudio signals from transmitting on the transmitter if one of theplurality of audio signals is being transmitted.
 2. The apparatus ofclaim 1 wherein the audio processor receives a request-to-transmitsignal from each of the plurality of audio devices seeking to transmit,and wherein the audio processor checks to determine if any otherrequest-to-transmit signals are enabled to determine if one of theplurality of audio signals is being transmitted.
 3. The apparatus ofclaim 1 wherein the audio processor prevents the other of the pluralityof audio signals from transmitting by preventing the other of theplurality of audio signals from passing to the transmitter.
 4. Theapparatus of claim 1 wherein the audio processor further allows anotherof the plurality of audio signals to transmit when the one of theplurality of audio signals being transmitted ceases to be transmitted.5. The apparatus of claim 1 wherein the plurality of audio devicescomprises a plurality of audio devices designed to receive communicationfrom crew members on an aircraft.
 6. An apparatus comprising: a) a bus,the bus transmitting a bus signal to a plurality of audio devices; b) anaudio processor coupled to the bus, the audio processor receiving atleast one warning signal, the audio processor converting said at leastone warning signal to a digital signal and transmitting the converted atleast one warning signal on the bus to the plurality of audio devices.7. The apparatus of claim 6 wherein the at least one warning signalincludes a ground proximity warning signal.
 8. The apparatus of claim 6wherein the at least one warning signal includes a collision avoidancewarning signal.
 9. The apparatus of claim 6 wherein the at least onewarning signal includes a fire warning signal.
 10. The apparatus ofclaim 6 wherein each of the plurality of audio devices includes amicrophone input and a speaker output, and wherein the plurality ofaudio devices transmit communication signals on the bus to providecommunication between crew members.
 11. An apparatus comprising: a) anaudio volume sensing device, the audio volume sensing device determiningan output volume for an aircraft audio communication device; b) a visualnotification device, the visual notification device activated when theaudio volume sensing device determines the output volume for theaircraft audio communication device is below a predetermined level. 12.The apparatus of claim 11 wherein the aircraft audio communicationdevice includes a speaker output and a headset output, and wherein theaudio volume sensor monitors the speaker output volume and the headsetoutput volume.
 13. The apparatus of claim 1I1 wherein the audio volumesensing determining when an output volume for an aircraft audiocommunication device determines when the audio communication device isoff.
 14. The apparatus of claim 11 wherein the visual notificationdevice displays text indicating the output volume is below thepredetermined level.